Saturday, May 16, 2015

ADF and Two-Way WebSocket Communication Architecture

This post is based on WebSockets and ADF, topic described in the previous post - WebSocket Integration with ADF for PPR Request Monitoring. I would like to look into it from technical architecture perspective and split WebSockets server logic into separate application deployed on WebLogic. WebSocket is two-way (bidirectional) communication channel, this allows to send and received data at the same time. I'm going to demonstrate how it works with my sample application.

It is best to explain how WebSocket works, with a live demo - you can watch recorded screencast. I'm using Twitter stream, you should see how many tweets are coming in for music category. Each tweet location is sent through WebSocket channel to ADF page, where it is rendered on the UI, through Java Script. ADF UI performance is measured in Java Script and logged back to the server through the same WebSocket channel. Tweet locations are coming from the server to ADF UI and ADF UI performance statistics traveling back to the server, at the same time:


I'm pretty amazed, how WebSocket transfers data - you should see how quick output text value is changing in ADF UI.

Download sample application - ADFAltaApp_v5.zip. Below diagram describes the main idea of this example:


There are two applications deployed on WebLogic 12c server. WebSocket server side application is listening for Twitter stream and sends data to the WebSocket client running in ADF UI. Logged performance data in ADF UI is sent back to WebSocket server side application.

Twitter stream handler is implemented as a servlet. It listens for every tweet received for the given topic and invokes WebSocket method to send data to the client:


Data is sent to the client using WebSocket API (library is available out of the box in WebLogic 12c and JDeveloper 12c). Incoming message is handled by another method - processMessage. This method accepts complex type, sent from ADF UI in JSON format:


Make sure to define WAR deployment profile for WebSocket project, this must be deployed as part of EAR. There should be deployment profile set, later referenced from WebSocket client:


WebSocket client runs in Java Script, there is onMessage function to handle incoming data. Here I'm simply setting newly received text as value for the ADF output text component:


ADF output text is empty initially, value is populated on runtime through WebSocket:


WebSocket communication from ADF UI to WebSocket server side is initiated in Java Script. PPR request timing data is written to JSON format and sent over WebSocket channel:

2 comments:

XxItzMythicxX said...

Hi Andrejus Baranovskis,

Thanks for these great web socket tutorials. I am having one issue you may be able to help with. I have created a web socket project as detailed in the above tutorial. I would now like to deploy this project to a jar and reference it from another war project. Is this possible?
In my own testing when deploying the new War which contains the web socket jar reference the endpoint does not resolve with context-root/socketpath of the new war. Any pointers you might have on this would be great. Thanks Again.

Andrejus Baranovskis said...

I'm planning to post future blog about this topic.

Andrejus